DESCRIPTION (adapted from the applicant's description): The goal of this proposal is to refine the understanding of the function and molecular pharmacology of T-type Ca channels. The experimental approach utilizes the patch clamp technique to study the biophysics and second messenger modulation of the first two cloned T-type Ca channels, alpha1H and alpha1G, heterologously expressed in HEK 2993 cells. There are four specific aims. Specific aim 1 identifies the metabolites of arachidonic acid (AA) metabolism that mediate blockade of T-type Ca channels. Specific aim 2 evaluates the contribution of PKC/G protein modulation of T-type Ca channels. Specific aim 3 defines the molecular transitions that underlie isoform-specific current kinetics and access the mechanism of channel modulation. Specific aim 4 proposes to identify the sites of the interaction between second messengers and T-type Ca channels.